Study links LED streetlights to breast and prostate cancer

BLUE LIGHT from LED street lights is linked to a ‘significant increase' in the risk of breast and prostate cancer, new research has concluded.

A study led by the Barcelona Institute for Global Health and involving the University of Exeter found that participants living in large cities with heavy exposure to blue lights at night had double the risk of prostate cancer and 1.5 times higher risk of breast cancer. This was compared to populations with less exposure to blue light.

The researchers found the bluer the light emission that people in large cities were exposed to, the higher the risk of cancer. The study also found that people who lived in homes with darker rooms, by using window shutters for example, had lower risk than those who did not.

In the first study of its kind, outdoor levels of artificial light were evaluated based on night-time images taken by astronauts aboard the International Space Station. Pic: Nasa

The study, published in Environmental Health Perspectives includes medical and epidemiological data of more than 4,000 people between 20 and 85 years of age in 11 Spanish regions. It particularly examined Madrid and Barcelona.

Indoor exposure to artificial light was determined through personal questionnaires. In the first study of its kind, outdoor levels of artificial light were evaluated based on night-time images taken by astronauts aboard the International Space Station.

Dr Alejandro Sánchez de Miguel, of the University of Exeter, told Lux: 'Humans have evolved to need light during the day and darkness at night. As towns and cities replace older lighting, we’re all exposed to higher levels of blue lights, which can disrupt our biological clocks. 

‘It’s imperative that we know for sure whether this increases our risk of cancer. Scientists have long suspected this may be the case – now our innovative findings indicate a strong link.

‘We must also investigate whether night-time exposure to the blue light emitted by smartphones and tablets increases our risk of cancer. We must now improve our research methods to ensure this is robust so we can advise on how best to protect human health. Currently, the images taken by astronauts on the International Space Station are our only way of determining the spread of blue light-emitting white LEDs in our cities.’

Little is known about how environmental factors affect breast and prostate cancer. The researchers hypothesise that LED lights may disrupt the body’s 24-hour cycle known as the circadian rhythm, in turn affecting hormones. Both breast and prostate cancer are hormone-related.

Previous research has shown an increased risk between prostate cancer and night shift work. It is also known that artificial light, particularly in the blue spectrum, can decrease the body’s production and secretion of the hormone melatonin.

Melatonin plays a key role in regulating the day-night cycles and has several other key functions, for example it is a powerful anti-oxidant and has also an anti-inflammatory function. However, its role in breast and prostate cancer is not yet understood.

Manolis Kogevinas, Barcelona Institute for Global Health researcher and coordinator of the study, said: ‘The World Health Organisation’s International Agency for Research on Cancer (IARC) has classified night shift work as probably carcinogenic to humans. There is evidence pointing to an association between exposure to artificial light at night, disruption of the circadian rhythm, and breast and prostate cancers.

‘With this study we sought to determine whether night exposure to light in cities can affect the development of these two types of cancer.’

Martin Aubé, physics professor at CÉGEP in Sherbrooke, Canada and study co-author, said: ‘We know that depending on its intensity and wave length, artificial light, particularly in the blue spectrum, can decrease melatonin production and secretion.’

The study was conducted within the framework of the MCC-Spain project cofunded by the ‘Consorcio de Investigación Biomédica en Red de Epidemiología y Salud Pública’ (CIBERESP).

Ariadna García, Barcelona Institute for Global Health researcher and first author of the study, says: ‘Given the ubiquity of artificial light at night, determining whether or not it increases the risk of cancer is a public health issue.

‘At this point, further studies should include more individual data using for instance light sensors that allow measuring indoor light levels. It would also be important to do this kind of research in young people that extensively use blue light emitting screens.’

Read the full research paper HERE.


  • Urban lighting is the subject of the new Safer Cities Conference which takes place on Wednesday 13 November and Thursday 14 November 2018 at the LuxLive exhibition at London ExCeL. For more information on the event, click HERE.

Comments 12

Shame on the supposed 'independent guide to lighting' promoting this rubbish, which will no doubt get picked up by unscrupulous hacks after a sensational story. Come on Lux, you should be better than this.

High street lighting correlates with dense urbanization. Dense urbanization correlates with automotive pollution and elevated anxiety about crime. Ergo, automobile pollution and anxiety cause cancer. Q.E.D.

This sort of studies increases the risk for honest scientists to get brain cancer.

To Eric Bretschneide It almost sounds like the "research" report is actually showing the effects of exposure to Mercury and/or Metal Halide street lamps. This would follow the time line of cells becoming cancerous that you have described.

NUTS ! Off the deep end and into the shallow end of the gene pool. Whoever was associated with this "study" should be stripped of their academic standing and made to write on the black board > 500 times " I'm very sorry for being so mentally lazy and scientifically ignorant I don't deserve to have any rank higher than an AS. in B.S. & P.R." I can't even credit the "findings" with being benign in presentation or content, as they are not and in fact, embarrass and discredit reputable researchers everywhere. This went out on the internet and that is how urban legend crap gets into a trusting society. It makes work for the rest of us to then do the damage control of the created mess ! Where is the peer review or any check and balance on this type of "publication" ? Has it gone this far south ? Best, Dr. Bob

What is missing is any description of any other data relating to lifestyles or any other variables. At best this is a chunk of really shabby research, at worst it is a total fabrication. For certain it is a classic demonstration of "The method of selected data." The fact that some people hate blue light because it is stimulating and leads to greater energy levels is also rather blatantly obvious. So why even print such garbage??

Yeah, I don't believe that report for a second. Whoever did this report has some other agenda.

A classic case of Bad Science.

What a crazy report about cancer. Let us throw away all mobile phones, TV, computers, etc, etc. Let say that cancer is related to drugs and alcohol. Other cancer causing products are prescribed drugs and vaccines. What about anti-depressants link to death and cancer, could this be possible? God help us with all the lies or half truth fostered in the general public.

This study screams to be peer reviewed. While there are studies that have established the general health risks of people working night shifts (with connects to pineal melatonin level changes), this study doesn't correlate to the quality of light alone, as opposed to just living in an urban setting and working at night. What about the period of time when most street lighting was metal halide blue? What about the natural blue of the light reflected from the moon? That's daylight blue too. What about the television and computer displays that are all high color-temperature (8,000K - 10,000K) sources that we look at for many hours a day - into the evening? To try to point to daylight CCT LED street lighting as the new source of increased cancer levels is questionable at best. Without better evidence to the contrary, I don't sufficient evidence to support the premise of this study or its findings.

Well said, Eric. I doubt any of us dispute that light intrusion effects sleep, and that disrupted sleep leads to health issues. Unless I'm misreading the context, it appears there are big reveal sentences on the right side of page 9 that seem to be overlooked in reporting and headlines: Visual response that we and others have used to evaluate the outdoor visual-ALAN is not necessarily well correlated to blue light, which is the light spectrum most likely to be relevant when evaluating biological responses related to cancer. In this population there was no correlation between estimates of outdoor visual light with blue light exposure. In the lighting industry, we've all seen plenty of aerial HPS vs LED city photos. If the ISS pictures are true-enough color (I believe it states they are 3-channel visible, so RGB) it would also seem to clearly indicate how little of the city is employing LED streetlights in those periods. The study really looks to be more along the lines of "raising questions with enough data thrown at it to justify funding for more studies". LED streetlights a popular boogey-man to pin it on.

The very first LED streetlights were introduced to the marketplace about a decade ago. Large scale adoption of LED streetlighting has only occurred in the last 5 years. Recent studies based on DNA sequencing of populations of cancer cells (within a patient) indicates that the progenitor cells for metastatic cancers develop years and decades before the cancers are detected. In summary, the genetic changes that lead to detectable cancers today occurred before LED streetlights could have had an impact. While there may be a link, correlation does not prove causation. With that I also point out the largest correlation coefficient (r^2) was on the order of 0.03. If you also look at the data, it is far from uniformly distributed. There is a large fraction of point in almost the same location and relatively few at higher light levels - exactly the scenario that allows a minority of data to dominate the result.

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